1. Field of the Invention
This invention relates to a pneumatic tool, and more particularly to a pneumatic impact tool.
2. Description of the Related Art
Referring to FIG. 1, a conventional pneumatic impact tool 1 disclosed in US2011/0139474A1 includes a housing 11, a transmission unit 12 extending along an X-axis and disposed rotatably in the housing 11 for power transmission, and a power output unit 13 extending along a Z-axis, disposed rotatably in the housing 11, and geared to the transmission unit 12. The housing 11 has a first accommodating chamber 111 receiving the power output unit 13, a second accommodating chamber 112 receiving the transmission unit 12, and an oil inlet 113 in fluid communication with the second accommodating chamber 112 and permitting lubricating oil to be fed therethrough.
When the transmission unit 12 is driven by a power source (not shown), such as a pneumatic cylinder, to rotate, due to the geared connection between the transmission unit 12 and the power output unit 13, the power output unit 13 is rotated for outputting a power. The lubricating oil flows from the oil inlet 113 into clearances among the components of the transmission unit 12 in the second accommodating chamber 112, and subsequently into clearances among the components of the power output unit 13 in the first accommodating chamber 111. As such, all of the rotating members of the pneumatic tool 1 can be lubricated to facilitate smooth rotation thereof.
However, the lubricating oil is made of grease, and thus is difficult to flow. Hence, during rotation of the transmission unit 12 and the power output unit 13, the lubricating oil is easily thrown away from the transmission unit 12 and the power output unit 13, thereby resulting in high temperature effect and, thus, reduced viscosity of the lubricating oil. That is, the lubricating effect is reduced.
Importantly, since only one oil inlet 113 is provided, and since it is disposed at a side of the second accommodating chamber 112 distal from the first accommodating chamber 111, when the lubricating oil is fed into the second accommodating chamber 112, it is difficult to fill the first accommodating chamber 111, so that a large amount of lubricating oil needs to fill the second accommodating chamber 112 in order to be squeezed into the first accommodating chamber 111, thereby resulting in inconvenient oil filling and an increase in the demand quantity of the lubricating oil, which is not cost effective.